1. Field of the Invention
The present invention relates to a two-wheeled motorcycle of a type in which a power unit is enveloped by a shell constituting at least a part of the chassis.
2. Description of the Prior Art
In two-wheeled motorcycles, the acceleration performance, driving performance and various other performances are largely affected even by a slight change of the weight, and various measures have been taken to reduce the weight of the two-wheeled motorcycles. Reduction of weight has almost reached a limit in the conventional construction of two-wheeled motorcycles in which the chassis frame is made up of steel pipes or plates with the power unit mounted thereon. A minimum weight is necessary to provide sufficient strength for the frame.